Carbon-Based adsorbents for heavy metal removal in Wastewater: Green technology or environmental Burden?

Water pollution from industrial, agricultural, and municipal sources demands effective and sustainable treatment solutions. Carbon-based adsorbents, such as activated carbon, biochar, carbon nanotubes, and graphene, offer promising pollutant removal capabilities due to their high adsorption capacities and versatility. However, their energy-intensive production, emissions, and challenges in regeneration raise concerns about environmental sustainability. This is the first study to provide a comprehensive evaluation of both the performance and environmental trade-offs associated with carbon-based adsorbents. Novelty of this study presents a new perspective, highlighting the double-edged nature of these materials—they offer significant pollutant removal potential but impose environmental burdens through energy consumption and chemical waste. It explores key applications, challenges, and trade-offs, such as variability in adsorption efficiency, high production costs, and risks of nanoparticle toxicity. Additionally, this study emphasizes the need for green production processes, composite adsorbents, and sustainable regeneration technologies to optimize their use. This review contributes a new perspective by addressing the dual role of carbon-based adsorbents as both solutions for and contributors to environmental challenges, providing actionable insights for advancing their application in sustainable water treatment systems.